The present invention relates to a connector comprising a central contact, an insulating housing having a contact inserting hole into which the central contact is press-fitted, and an external contact adapted to engage with the insulating housing by insertion therein of the insulating housing with the central contract press-fitted therein. For example, the present invention is concerned with an automobile antenna plug connected to an end portion of a coaxial cable.
Heretofore, as this type of a connector there has been known such a coaxial connector as shown in FIGS. 1A to 1C and FIGS. 2 and 3, which connector is disclosed, for example, in Japanese Patent No. 3059432 issued Jul. 4, 2000.
More particularly, such a plug pin 100 as shown in FIG. 1A, which serves as a central contact, is press-fitted into a cylindrical hollow portion 104 from behind an insulating housing 102, as shown in FIG. 1B. At this time, a pair of retaining projections 106 and a pair of retaining projections 108 of the plug pin 100 bite into engagement with an engaging rib (not shown) projecting from an inner wall surface of the insulating housing 102, whereby the plug pin 100 is fixed within the cylindrical hollow portion 104 of the insulating housing 102.
Then, an assembly 110 thus obtained is inserted into an external contact 112, as shown in FIG. 1C. When an engaging lance 114 of the external contact 112 gets over an engaging stepped portion 116 of the insulating housing 102, both come into engagement with each other as in FIG. 3 and the external contact 112 is fixed to the outside of the insulating housing 102.
Next, as shown in FIG. 2, a braided conductor (shielded conductor) 73 of a coaxial cable 7 and a central conductor 71 are exposed and the central conductor 71 is connected to a connecting portion 120 of the plug pin 100, thereafter, the braided conductor 73 is connected to the external contact 112.
The connection of the central conductor 71 to the connecting portion 120 is performed in the following manner.
The central conductor 71 of the coaxial cable 7 is disposed above an engaged portion between a first engaging contact piece 122 and a pair of second engaging contact pieces 124 of the plug pin 100, then the first and second engaging contact pieces 122, 124 are pushed and expanded using a jig (not shown) and the central conductor 71 is conducted into concaves of the second engaging contact pieces 124, followed by removal of the jig, whereby, as shown in FIG. 3, the central conductor 71 is held grippingly between the first and second engaging contact pieces 122, 124 and is connected electrically to the plug pin 100.
Connection of the braided conductor 73 to the external contact 112 is performed in the following manner.
A pair of inner compression-bonding pieces 126 of the external contact 112 are inserted between an internal insulator 72 and the braided conductor 73 of the coaxial cable 7 and then a pair of outer compression-bonding pieces 128 are caulked, whereby the braided conductor 73 and the external contact 112 are integrally fixed and connected to each other electrically, as shown in FIG. 3.
Then, a pair of coating compression-bonding pieces 130 are caulked on an outer insulating coating 74 of the coaxial cable 7 to fix the whole of the coaxial cable 7 to the external contact 112, as shown in FIG. 3.
The numeral 132 denotes a cover piece which is bent to cover the connecting portion 120 from above, numeral 134 denotes an insulating cover for covering an outer periphery surface of the external contact 112, numeral 136 denotes an insulating cap which is fitted on the coaxial cable 7 beforehand and brought into engagement with the insulating cover, and numeral 138 denotes a contact tongue piece provided in a pair which is projected from a window hole formed in the insulating cap and comes into contact with an earth terminal of a mating connector.
However, in the conventional connector shown in FIGS. 1A to 1C and FIGS. 2 and 3, the plug pin 100 is press-fitted into the cylindrical hollow portion 104 of the insulating housing 102 and its retaining projections 106 and 108 are merely allowed to bite into engagement with the engaging rib projecting from the inner wall surface of the insulating housing 102 to retain the plug pin. Thus, there has been the problem that the fixing strength between the plug pin 100 and the insulating housing 102 is not sufficient and that therefore the plug pin 100 is apt to come off from the insulating housing 102.
Particularly, in a standard type connector to which a relatively thick coaxial cable is connected, a base end-side outer periphery portion of a semispherical tip of the plug pin is formed in the shape of an annular recess to increase the holding force at the time of fitting with a mating connector (e.g., an automobile antenna socket), so that a relatively large tensile force is exerted on the plug pin, thus giving rise to the problem that the plug pin is apt to come off from the insulating housing.